Refrigerating apparatus



Feb. v9, 1937. L, CHASE 2,070,330

REFRIGERATING APPARATUS Filed Aug. 31, 1931 I l 7 I l n INV NTOR m M ms ATTORNEYS.

Patented Feb. 9, 1,937 i uNiTED STATES PATENT oFFiCE REFRJGERATING APPARATUS Frederic L. Chase, Dayton, Ohio, assgnor, by

mesn'e assignments, to General Motors Corporation, a, corporation of Delaware Application August 31, i931, serial No. 560,337

s claims. (ci. 154-28) This invention relates to refrigerating appara.- In the drawing: tus-and more particularly to a method of manu- Fig. 1 lis a sectional view of a refrigerator facturing heat insulated wall structures for use cabinet embodying features of my invention, the in the manufacture of refrigerating cabinets. section being taken on aline beyond the door One of the most important problems connected opening; 5 with the manufacture of refrigerator cabinets is Fig. 2 is a sectional view of a second cabinet the provision of means for excluding moisture showing additional features, the -section being from accumulating within the confines of the likewise taken on a line beyond the door opening; Wall structure, for example, within the insulating Fig. 3 is a diagrammatic section of a wall struc- A material itself or on the surface of the cold liner. ture showing the results of one manner of ap- 10 The tendency for moisture to condense within the plying the esphaltie materiel;

Wall structure is obviously inherent in all such Fig. 4 iS a diegrammatie SeCtiOn 0f a Wall Struecabinet constructions for since the interior of the ture showing the results of a second manner of cabinet is maintained at a. temperature considerapplying the asphaltic material, and y l5 ably lower than the temperature of the surround- Fig. 5 is a diagrammatic section of the results l5 ing atmosphere, there is quite a large temperature of a third set of operating conditions. gradient between the interior and exterior walls In order to illustrate my invention and the of the cabinet. On this gradient and conseimportance it plays in the manufacture of heat quently within the wall structure there occurs a insulated refrigerator cabinets, I have disclosed temperature called the dew point, at which point in Figs. 1 and 2, refrigerator Cabinets. These the moisture in the air tends to condense. Such cabinets are shown as having a 'frame Structure condensation is detrimental to the long life of composed of wood corner post members I0 and the cabinet structure for it not only increases the Carried by said frame and an inner metal lining heat conductivity of the wall butalso tends to Il, and an outer metal covering l2 With a bleek break down the insulating structure itself. or slab of corkboard or rock cork I4 therebetween. 2

With these difficulties in mind, it has been the In such a construction the lining i bounding the practice heretofore to attempt to waterproofthe cold compartment iS re12-tiVe1y Cold and tendS .t0 wall structures to prevent the passage of water draw and condense moisture from the Warmer Vapor from the surrounding atmosphere to the outside atmosphere into and within the insulating point at which condensation takes place. For slab I4. For this reason,.the insulating slab I4 30 this purpose it has been the practice t0 apply is sealed against the ingress of moisture from the asphaitic material such as a pitch-like bituminous warmer atmosphere by means 0f asphaltie matecompound known to the trade under various rial. As shown in Fig.'1, the insulating material names, one of which is hydrolene, to the walls may be Sealed by a layer 0f asphalte material I6 A of the cabinet and insulating material. Heretobetween the lining and the Slab I4 and around 35 fore, this asphaltic treatment has not been satisthe Guter SurfaceS 0f the Slab I4, 0r, as Shown in factory and in practically all cases of unsatis- Fig. 2. the asphalt I6 may be only 0n the eXternal factory results, the trouble has been caused by exposed surfaces of the insulating material. improper methods of applying the asphaltic The pertieuial methods by Which the Cabinets 40 material to the insulation are assembled and the insulation is sealed there- 40 It is the purpose and object of my present inon are not of importance as far as my invention vention to overcome the defects of prior methods iS eeneei'ned- F01' example. the Cabinet may be of applying asphalt to insulating material by assmbled and the msillatlon Sealed by msi" ap' controlling the conditions governing the applipiymg a' layer or Cofitmg o? asphalt to tlhe out" cation oi theasphalt, particularly the tempera- 51de Surfac? of me mner hrung Hy Coatmg one 45 ture at which the asphalt is applied side of the insulatlngslab and pressing the coated In order to more clearly disclose my invention, Slab 'agausttlhe lmnl'rf Asphfal may lthn be I have illustrated certain wall structures on the pome on o e ou ,ers ace o e insu anon )6.o u produce the structure disclosed 1n Fig. l. Or, 1f attached dafivmg' the structure disclosed in Fig. 2 is desired, the 50 Further objects and advantages of the present slab I4 is placed on the liner Il and the layer mven'tlof Wm be apparnt from the followmg of asphalt sprayed or painted on the outside surdesorlptlon. reference belng had t0 the aCCOmface thereof. Still another method would be aspanying drawing. wherein a preferred form of the sembling the inner and outer walls H and l2 present invention is clearly shown. with the insulation therebetween and subsequently f pouring in the asphalt in a molten condition between the lining II and insulation I4 and/or between the outer wall I2 and the insulating slab.

Heretofore, all attempts at-sealing the insulating material by means of asphalt have been unsatisfactory for the reason that the conditions governing the application of the asphalt have not been correctly controlled.

I have found that the temperature at which the asphalt is applied is most important. For example, if the temperature at which a specific asphaltic compound is applied is too high, then the degree of penetration of the asphalt into the block of insulating material is too great, thereby improperly sealing the slab against the ingress of moisture and consequently resulting in a poor construction as set forth above.

Such a condition is clearly shown in Fig. 3,

` wherein it is apparent that the asphalt indicated at 40 has penetrated to great depths in the insulating material I4. Since the insulating properties of asphalt are not as good as those of cork- Y board, it follows that the insulating effect of the corkboard has been decreased. It is also apparent that the amount of asphalt remaining attached to the surface of the corkboard as indicated at 42 is insumcient to properly seal the corkboard against ingress of moisture. Consequently, under such conditions, after the Wall has been assembled, air and consequently water vapor will be drawn into the wall structure, resulting in the condensation of moisture therein. It is just such a condition that results in a rapid deterioration of the insulating material as set forth above.

If, on the other hand, the temperature is too low, the degree of penetration is so little as to cause improper adhesion of the asphalt to the 'corkboard slab, such a construction results in the separation of the asphaltic material from the insulation during use of the cabinet and consequently improper sealing of the material I4.

Such a condition is shown exaggerated in Fig. 4,` wherein it will be noticed that the asphalt has not penetrated the corkboard at all and under such conditions a proper bond between the liner and the corkboard is impossible. Such a condition usually results in a shifting of the insulating material with the consequent formation of heat leaks.

As a specific example of my invention, the asphaltic compound may be a pitch-like bituminous product, or, in other words, a refined petroleum product free from ller or other material and having a softening point not less than 180 F. and not more than 200 F. I have found that with such an asphaltic compound, if the temperature of the asphalt is maintained at substantially 350 F.-365 F. during the entire act of applying the asphalt to the insulating slab, the ideal condition as indicated in Fig. 5 is obtained. That is to say, the penetration of the asphalt 40 into the insulating block I4 will be suiiicient to cause a proper adhesion of the asphalt to the block and thereby obtain proper sealing thereof while at the same time it will not be great enough to substantially impair the insulating qualities of the insulating block. At the same time the as- Dhalt will adhere` to the insulating block and will produce a thick substantiallyl smooth layer 42 of asphalt thereon having a/vey glossy appearance and substantially free from# air "'spaces.

I have found that if the temperature' of the asphaltic material is below approximately ,350 F. when working with the specific examplegiven above, that the degree of penetration is insuiiicient to cause ,proper adhesion of the asphaltic material to the insulating material, the result being substantially as shown in Fig. 4. On the other hand, if the temperature of the asphaltic material is allowed to rise much above 365 F., for example 375 F., then the layer of asphaltic material begins to get uneven and rough, conforming substantially to the uneven surface of the insulating block as shown in Fig. 3. At this temperature the finish is still glossy but air spaces appear therein indicating that the degree of penetration has passed the desired degree. At

400 F. and temperatures above 400 F., the finish is dull and the penetration is such as to leave substantially no layer of asphaltic material on the insulating slab.

A glossy substantially smooth layer of asphaltic material free from air spaces, may be taken as an indication of proper temperature at which the asphaltic material should be applied.

There are on the market various products having substantially lthe properties of the asphaltic material specifically mentioned above. Some of these asphaltic materials soften at a temperature below 180 F. while others soften at a temperature above 200 F. When dealing with an asphaltic material melting below 180 F., obviously the temperature at which such a material will be applied to the insulating material will be substantially lower than 350 F. Likewise, when dealing with an asphaltic material whose softening point is above 200 F., the temperature at which the asphaltic `material will be applied to the insulating material will be above 365 F. With any asphaltic material, however, the temperature at which the material is applied to the insulating material should be maintained substantially at that temperature which will give a smooth glossy layer of asphalt substantially free from air spaces and properly adhering to the insulating material.

While I have disclosed one specific asphaltic material and various methods by which this asphaltic material may be applied to insulating material, it should be understood that my invention relates generically to the step of controlling the temperature at which application takes place to provide a smooth glossy layer of asphaltic material on the insulating material, thereby providing proper sealing of the insulating material from the atmosphere and thereby overcoming the fault that has caused practically all refrigerator cabinet difficulties heretofore.

While the form of embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

l. That step in the art of applying asphalt to insulating material which comprises maintaining asphalt and applying the asphalt to the insulating material at a temperature giving only suiicient penetration to cause adhesion of the asphalt to the insulating material while providing a smooth glossy layer of asphalt thereon to protect the insulation from moisture.

2. The method of coating insulating material with an asphaltic material having a softening point between 180 F. and 200 F. which comprises heating the asphaltic material to substantially 350 F.-365 F. and applying the asphalt to the insulating material while maintaining the temperature of the asphalt to be applied substantially constant at this temperature during f the entire act of applying the asphalt to the insulating material.

3. The method of coating or applying pitchlike asphaltic material to insulation which comprises heating the asphalt to a temperature above its softening point and applying the asphalt to the insulating material while maintaining the temperature of the asphalt to be applied substantially constant at the point where a substantially smooth, glossy adherent layer of asphalt is formed on the insulation.`

4. The method of insulating and sealing the insulation of a refrigerator cabinet which comprises applying a coating of asphaltic material having a softening point between 180 F. and 200 F. at a temperature of between 350 F. and 365 F. to the outer surface of the inner liner; applying a slab of insulation to the outer surface of the inner liner so coated while maintaining the asphaltic material to be applied at substantially between 350 F. and 365 F.; and then applying the asphaltic material having a softening point between 180 F. and A200 F. at a temperature of substantially between 350 F. and 365 F. to the outer surface of the slab of insulating material.

5. The method 0f insulating and sealing the insulation of a refrigerator cabinet which comprises applying a slab of insulating material to the outer surface of the inner liner; and applying asphaltic material to the outer surface 0f the insulation at a substantially constant temperature at the point Where a substantially smooth, glossy adherent layer of asphalt is formed on the insulation.

6. The method of coating a cork insulating material with an asphaltic material having a softening point between 180 F. and 200 F. which comprises heating the asphaltic material to substantially 350 F.365 F. and applying the asphalt to the insulating material while maintaining the temperature of the asphalt to be.

applied substantially constant at this temperature during the entire act of applying the asphalt to the insulating material to obtain a slight but adequate penetration of the asphalt in the insulating material and a smooth glossy surface coating of the asphalt.

FREDERIC L. CHASE. 

